Unintentional Touch Rejection

ABSTRACT

A method for rejecting an unintentional palm touch is disclosed. In at least some embodiments, a touch is detected by a touch-sensitive surface associated with a display. Characteristics of the touch may be used to generate a set of parameters related to the touch. In an embodiment, firmware is used to determine a reliability value for the touch. The reliability value and the location of the touch is provided to a software module. The software module uses the reliability value and an activity context to determine a confidence level of the touch. In an embodiment, the confidence level may include an evaluation of changes in the reliability value over time. If the confidence level for the touch is too low, it may be rejected.

PRIORITY CLAIM AND CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from and is a continuation of U.S.patent application Ser. No. 11/324,157, filed on Dec. 30, 2005, which isincorporated by reference herein.

BACKGROUND

Touch-sensitive devices are becoming widespread in computing devices asa means of input, especially computing devices that are intended forportable use. Touch-sensitive devices are very convenient as they allowa user to make natural gestures familiar to the user in other contexts,such as by entering handwriting using a dedicated stylus in a mannersimilar to using a pen. While this provides a natural feel for the use,one potential problem with a dedicated stylus is that it can be lost. Ascan be appreciated, this is problematic if the dedicated stylus isrequired in order to electronically write or ink on the touch-sensitivedevice. Another potential problem is that it may be inconvenient toretrieve the stylus from its storage location when needed for onlyoccasional use. Therefore, many of the computing devices includetouch-sensitive surfaces that allow input to be provided by a variety ofstylus types, including a user's fingertip. Accordingly, the termtouch-sensitive surface or device will be used herein to refer to suchsurfaces or devices that are configured to detect the touch of any orall stylus types. While generally a convenient feature, a disadvantageto this ability to accept input from a variety of stylus types is thatit is likely that the user will, from time to time, inadvertently touchthe touch-sensitive surface with the user's finger, hand, etc., whilewriting on the device. This may also happen while the user is holding orotherwise handling the device. Users may find that these inadvertenttouches perform undesired actions.

SUMMARY

In at least some embodiments an unintentional touch on a touch-sensitivedevice is automatically rejected. A touch is detected and a set ofparameters related to the touch may be generated. The set of parametersmay be used to determine a reliability value for the touch. Thereliability value may be transmitted to a software module and thesoftware module can determine a confidence level based on thereliability value and an activity context. The confidence level mayinclude a determination of changes in the reliability over time.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is illustrated by way of example and not limitedin the accompanying figures in which like reference numerals indicatesimilar elements and in which:

FIG. 1 illustrates a schematic diagram of an exemplary general-purposedigital computing environment in which certain aspects of the presentinvention may be implemented.

FIG. 2 illustrates an embodiment of a Tablet PC computing environment inwhich certain aspects of the present invention may be implemented.

FIGS. 3-4 illustrate embodiments of a computer in which certain aspectsof the present invention may be implemented.

FIG. 5 illustrates an embodiment of user interface with atouch-sensitive device in which certain aspects of the present inventionmay be implemented.

FIGS. 6-7 illustrate embodiments of touches on a touch-sensitive surfacein which certain aspects of the present invention may be implemented.

FIG. 8 a illustrates a method of rejecting an inadvertent touch that maybe used in accordance with one or more aspects of the present invention.

FIG. 8 b illustrates an alternative method of rejecting an inadvertenttouch that may be used in accordance with one or more aspects of thepresent invention.

FIG. 9 illustrates an embodiment of a set of touches on atouch-sensitive surface in which certain aspects of the presentinvention may be implemented.

FIG. 10 illustrates a depiction of data related to a series of touchesthat may be used in accordance with one or more aspects of the presentinvention.

FIG. 11 illustrates a schematic of an exemplary computing environmentthat may be used in accordance with one or more aspects of the presentinvention.

FIG. 12 illustrates a method for determining whether to reject a touchthat may be used in accordance with one or more aspects of the presentinvention.

FIG. 13 illustrates a method for evaluating a confidence level of atouch that may be used in accordance with one or more aspects of thepresent invention.

DETAILED DESCRIPTION Exemplary Computing Environment

FIG. 1 illustrates an example of a suitable computing system environment100 on which the invention may be implemented. The computing systemenvironment 100 is only one example of a suitable computing environmentand is not intended to suggest any limitation as to the scope of use orfunctionality of the invention. Neither should the computing environment100 be interpreted as having any dependency or requirement relating toany one or combination of components illustrated in the exemplaryoperating environment 100.

The invention is operational with numerous other general purpose orspecial purpose computing system environments or configurations.Examples of well known computing systems, environments, and/orconfigurations that may be suitable for use with the invention include,but are not limited to, personal computers, server computers, hand-heldor laptop devices, multiprocessor systems, microprocessor-based systems,set top boxes, programmable consumer electronics, network PCs,minicomputers, mainframe computers, distributed computing environmentsthat include any of the above systems or devices, and the like.

The invention may be described in the general context ofcomputer-executable instructions, such as program modules, beingexecuted by a computer. Generally, program modules include routines,programs, objects, components, data structures, etc., that performparticular tasks or implement particular abstract data types. Theinvention may also be practiced in distributed computing environmentswhere tasks are performed by remote processing devices that are linkedthrough a communications network. In a distributed computingenvironment, program modules may be located in both local and remotecomputer storage media including memory storage devices.

With reference to FIG. 1, an exemplary system for implementing theinvention includes a general purpose computing device in the form of acomputer 110. Components of computer 110 may include, but are notlimited to, a processing unit 120, a system memory 130, and a system bus121 that couples various system components including the system memoryto the processing unit 120. The system bus 121 may be any of severaltypes of bus structures including a memory bus or memory controller, aperipheral bus, and a local bus using any of a variety of busarchitectures. By way of example, and not limitation, such architecturesinclude Industry Standard Architecture (ISA) bus, Micro ChannelArchitecture (MCA) bus, Enhanced ISA (EISA) bus, Video ElectronicsStandards Association (VESA) local bus, and Peripheral ComponentInterconnect (PCI) bus also known as Mezzanine bus.

Computer 110 typically includes a variety of computer readable media.Computer readable media can be any available media that can be accessedby computer 110 and includes both volatile and nonvolatile media,removable and non-removable media. By way of example, and notlimitation, computer readable media may comprise computer storage mediaand communication media. Computer storage media includes both volatileand nonvolatile, and removable and non-removable media implemented inany method or technology for storage of information such as computerreadable instructions, data structures, program modules or other data.Computer storage media includes, but is not limited to, RAM, ROM,EEPROM, flash memory or other memory technology, CD-ROM, digitalversatile disks (DVD) or other optical disk storage, magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,or any other medium which can be used to store the desired informationand which can accessed by computer 110. Communication media typicallyembodies computer readable instructions, data structures, and programmodules or other data in a modulated data signal such as a carrier waveor other transport mechanism and includes any information deliverymedia. The term “modulated data signal” means a signal that has one ormore of its characteristics set or changed in such a manner as to encodeinformation in the signal. By way of example, and not limitation,communication media includes wired media such as a wired network ordirect-wired connection, and wireless media such as acoustic, RF,infrared and other wireless media. Combinations of the any of the aboveshould also be included within the scope of computer readable media.

The system memory 130 includes computer storage media in the form ofvolatile and/or nonvolatile memory such as read only memory (ROM) 131and random access memory (RAM) 132. A basic input/output system 133(BIOS), containing the basic routines that help to transfer informationbetween elements within computer 110, such as during start-up, istypically stored in ROM 131. RAM 132 typically contains data and/orprogram modules that are immediately accessible to and/or presentlybeing operated on by processing unit 120. By way of example, and notlimitation, FIG. 1 illustrates operating system 134, applicationprograms 135, other program modules 136, and program data 137.

The computer 110 may also include other removable/non-removable,volatile/nonvolatile computer storage media. By way of example only,FIG. 1 illustrates a hard disk drive 141 that reads from or writes tonon-removable, nonvolatile magnetic media, a magnetic disk drive 151that reads from or writes to a removable, nonvolatile magnetic disk 152,and an optical disk drive 155 that reads from or writes to a removable,nonvolatile optical disk 156 such as a CD ROM or other optical media.Other removable/non-removable, volatile/nonvolatile computer storagemedia that can be used in the exemplary operating environment include,but are not limited to, magnetic tape cassettes, flash memory cards,digital versatile disks, digital video tape, solid state RAM, solidstate ROM, and the like. The hard disk drive 141 is typically connectedto the system bus 121 through a non-removable memory interface such asinterface 140, and magnetic disk drive 151 and optical disk drive 155are typically connected to the system bus 121 by a removable memoryinterface, such as interface 150.

The drives and their associated computer storage media discussed aboveand illustrated in FIG. 1, provide storage of computer readableinstructions, data structures, program modules and other data for thecomputer 110. In FIG. 1, for example, hard disk drive 141 is illustratedas storing operating system 144, application programs 145, other programmodules 146, and program data 147. Note that these components can eitherbe the same as or different from operating system 134, applicationprograms 135, other program modules 136, and program data 137. Operatingsystem 144, application programs 145, other program modules 146, andprogram data 147 are given different numbers here to illustrate that, ata minimum, they are different copies. A user may enter commands andinformation into the computer 20 through input devices such as akeyboard 162 and pointing device 161, commonly referred to as a mouse,trackball or touch pad. Other input devices (not shown) may include amicrophone, joystick, game pad, satellite dish, scanner, or the like.These and other input devices are often connected to the processing unit120 through a user input interface 160 that is coupled to the systembus, but may be connected by other interface and bus structures, such asa parallel port, game port or a universal serial bus (USB). A monitor191 or other type of display device is also connected to the system bus121 via an interface, such as a video interface 190. In addition to themonitor, computers may also include other peripheral output devices suchas speakers 197 and printer 196, which may be connected through anoutput peripheral interface 195.

The computer 110 may operate in a networked environment using logicalconnections to one or more remote computers, such as a remote computer180. The remote computer 180 may be a personal computer, a server, arouter, a network PC, a peer device or other common network node, andtypically includes many or all of the elements described above relativeto the computer 110, although only a memory storage device 181 has beenillustrated in FIG. 1. The logical connections depicted in FIG. 1include a local area network (LAN) 171 and a wide area network (WAN)173, but may also include other networks. Such networking environmentsare commonplace in offices, enterprise-wide computer networks, intranetsand the Internet.

When used in a LAN networking environment, the computer 110 is connectedto the LAN 171 through a network interface or adapter 170. When used ina WAN networking environment, the computer 110 typically includes amodem 172 or other means for establishing communications over the WAN173, such as the Internet. The modem 172, which may be internal orexternal, may be connected to the system bus 121 via the user inputinterface 160, or other appropriate mechanism. In a networkedenvironment, program modules depicted relative to the computer 110, orportions thereof, may be stored in the remote memory storage device. Byway of example, and not limitation, FIG. 1 illustrates remoteapplication programs 185 as residing on memory device 181. It will beappreciated that the network connections shown are exemplary and othermeans of establishing a communications link between the computers may beused.

FIG. 2 illustrates an exemplary tablet PC 201 that can be used inaccordance with various aspects of the present invention. Any or all ofthe features, subsystems, and functions in the system of FIG. 1 can beincluded in the computer of FIG. 2. Tablet PC 201 includes a largedisplay surface 202, e.g., a digitizing flat panel display, preferably,a liquid crystal display (LCD) screen, on which a plurality of windows203 are displayed. Using stylus 204, a user can select, highlight,and/or write on the digitizing display surface 202. Examples of suitabledigitizing display surfaces 202 include electromagnetic pen digitizers,such as Mutoh or Wacom pen digitizers. Other types of pen digitizers,e.g., optical digitizers, may also be used. Tablet PC 201 interpretsgestures made using stylus 204 in order to manipulate data, enter text,create drawings, and/or execute conventional computer application taskssuch as spreadsheets, word processing programs, and the like.

The stylus 204 may be equipped with one or more buttons or otherfeatures to augment its selection capabilities. In one embodiment, thestylus 204 could be implemented as a “pencil” or “pen”, in which one endconstitutes a writing portion and the other end constitutes an “eraser”end, and which, when moved across the display, indicates portions of thedisplay are to be erased. Other types of input devices, such as a mouse,trackball, or the like could be used. Additionally, a user's own fingercould be the stylus 204 and used for selecting or indicating portions ofthe displayed image on a touch-sensitive or proximity-sensitive display.Consequently, the term “user input device”, as used herein, is intendedto have a broad definition and encompasses many variations on well-knowninput devices such as stylus 204. Region 205 shows a feedback region orcontact region permitting the user to determine where the stylus 204 hascontacted the display surface 202.

In various embodiments, the system provides an ink platform as a set ofCOM (component object model) services that an application can use tocapture, manipulate, and store ink. One service enables an applicationto read and write ink using the disclosed representations of ink. Theink platform may also include a mark-up language including a languagelike the extensible markup language (XML). Further, the system may useDCOM as another implementation. Yet further implementations may be usedincluding the Win32 programming model and the .Net programming modelfrom Microsoft Corporation.

Inadvertent Touch Rejection

Before discussing various embodiments, it should be noted that numeroustypes of touch-sensitive devices, such as touch-sensitive displays,exist. Touch-sensitive devices may detect changes in pressure, light,displacement, heat, resistance or capacitance, just to name a fewvariations. Furthermore, touch-sensitive devices may be configured todetect an input device such as a dedicated stylus when the dedicatedstylus is moved within a proximity zone. For example, a dedicated styluscould emit or retransmit a signal or could include a particular material(such as a magnet) or a particular configuration of a material (such asa coil) in a tip. Numerous variations are possible depending on thehardware used to detect the touch.

Looking at FIG. 3, an embodiment of a computer 110 in a typical laptopconfiguration is depicted. Somewhat similarly, FIG. 4 illustrates anembodiment of a computer 110 in a tablet configuration. As is known,variations in size and performance are possible, thus the depictedcomputers could be made smaller so as to fit within a user's pocket. Inaddition, some computers are configured to transition between laptop andtablet configuration. In addition, some computers may mount the displayseparately. In both depicted embodiments, however, a touch-sensitivedevice 165 is incorporated as part of the computer 110. As illustrated,the touch-sensitive device 165 is also a display; however the touchsensitive device 165 is not so limited. The touch-sensitive device 165includes a touch-sensitive surface 208 on which a stylus 204, which maybe a finger, can write, tap or provide other types of input.

In either configuration, it is expected that occasionally a person willinadvertently touch the screen with the person's hand while providinginput to the touch-sensitive surface. For example, typically a personwill rest a portion of their hand on the writing surface while writing.In certain embodiments, as discussed in greater detail below, this extratouch is determined to be inadvertent and is automatically rejected.

A touch-sensitive display can be configured to process the touch anddetermine whether the touch should be rejected based on characteristicsof the touch alone. For example, a display can compare the pressure andarea of the touch to determine whether the touch matches expected touchpatterns typically used for input. This single level of control, whileuseful, can also benefit from additional processing.

Turning to FIG. 5, an embodiment of an individual using atouch-sensitive display is depicted. The user is writing with adedicated stylus 204 and is holding a hand 415 over the touch-sensitivesurface 208 of the touch-sensitive device 165. It should be noted that,depending on the configuration, a housing 162 of the computer 110 mayalso be the housing of the touch-sensitive device 165. Alternatively,the housing 162 of the computer 110 may be split into portions that maybe connected, either indirectly or directly and either wirelessly orwired. Displayed on the touch-sensitive surface 208 is a first window530, a second window 535 and a third window 550. As is known, a windowrefers to a portion of a screen display associated with an applicationor with an OS process.

As can be appreciated, the dedicated stylus 204 is positioned so as toelectronically create ink (e.g. ink) on the first window 530 while thehand is positioned over the first window 430 and the second window 535.However, neither the hand 515 nor the dedicated stylus 204 is positionednear the third window 550. More will be said with respect to this below.

Turning to FIG. 6, a touch-sensitive surface 208 is depicted, thetouch-sensitive surface 208 being exemplary of what may be provided on atouch-sensitive display. Provided on the touch-sensitive surface 208 isa first touch 615 and a second touch 630. As can be appreciated, giventhe discrepancy in size and shape, it is relatively simple to reject thetouch 630 as being unwanted. For example, while a user's finger can comein a range of sizes, the touch 630 plainly exceeds such a range andtherefore a simple determination that the area of touch 630 exceeds apredetermined limit could be used to reject the touch. In an alternativeembodiment, the shape of the touch 630 may be used to determine thetouch was inadvertent.

Turning to FIG. 7, an embodiment of a touch-sensitive surface 208 isdepicted with alternative touches 715, 730 and 735. While the touch 715is slightly smaller than the touch 730 or touch 735, they all fit withina range of expected variations of a finger size and therefore it isdifficult to reject the touches as being inadvertent based on pressureand area alone. As can be appreciated, touches typically vary with time.Therefore, the touches 730 and 735, while initially resembling pointssimilar to what would be expected for a finger, may eventually grow toresemble touch 630.

In other words, because of the sampling frequency of the touch-sensitivedevice 165, which may be greater than 200,000 Hz, the touch-sensitivesurface 208 may initially detect a touch that resembles the touch 730 or735 (or both) and over time the detected touch will start to resemblethe touch 630.

Thus, a touch-sensitive device 165 (FIG. 5) might initially determinethat touch 715 and touches 730 and 735 were acceptable touches. In otherwords, the touch-sensitive device 165 would indicate that touches 730and 735 both had high reliability. In contrast, the touch-sensitivedevice 165 would indicate that touch 630 had low reliability. As can beappreciated, the change in the touch may affect the reliabilitydetermination. It should be noted that reliability may be based on themeasurable information relating to the touch such as, but not limitedto, pressure, area, rates of change in characteristics of the touch, andvelocity of movement, thus different touch-sensitive devices may usedifferent mechanisms for determining the reliability of a particulartouch based on their underlying technology. Furthermore, certaintouch-sensitive devices may be better at accurately determiningreliability for a particular touch or type of touch.

FIG. 8 a illustrates a method that may be used to determine whether toreject the touch 530. First in step 802 a touch is detected. Next instep 804, a check is made to see if the pressure applied by the touchexceeds some minimum. If it does, then in step 805 a check is made tosee if the touch is the appropriate size or shape. In at least someembodiments, this can be done by comparing the touch to a predeterminedset of sizes or shapes. If the touch meets the requirements of steps 804and 805, then in step 806 the touch is treated as an input andtransmitted to the appropriate software module. If the touch fails topass either step 804 or step 805, then in step 809 the touch isrejected.

As can be appreciated, however, the method of FIG. 8 a may be unable todetermine that certain types of inadvertent touches, such as the touch730, should be rejected. Therefore, a method as illustrated in FIG. 8 bmay be used.

First in step 820, a touch is detected. As noted above, the method ofdetecting the touch depends on the type of hardware chosen. Thus, aresistance based touch-sensitive surface would detect changes inresistance and a capacitance based touch-sensitive surface would detectchanges in capacitance. The present invention is not limited to aparticular type and therefore the decision of which type oftouch-sensitive device to use is primarily a design choice based ontradeoffs between different technologies and their respective costs andfeatures.

Next in step 825, a set of parameters are determined. The parameters mayinclude, but are not limited to, location of the touch, area of thetouch, shape of the touch, pressure of the touch, and number of pointsof contact of the touch. The parameters may also be specific to aparticular hardware such as change in resistance or capacitance. Itshould be noted that different parameters may have different ranges ofvalues, depending on the type of parameter. Thus, a parameter for areamay be in square meters while a parameter related to a change inresistance might be in ohms or volts.

It should be noted that, depending on the sampling frequency, twotouches that are related, such as two portions of the same palm, may nottouch the touch-sensitive surface at the same time. Therefore, twodistinct touches can be joined together if they are nearby or areinitially detected at about the same time. In addition, if two touches,such as the touches 730 and 735 of FIG. 7, move together they can alsobe determined to be part of the same touch.

In addition to the above parameters, derived parameters such as the rateof change in a parameter can also be determined. If a rapid samplingrate is used, the rate of change per sample may be relatively small buteven relatively small rates of change can be useful to determine whethera touch should be rejected. Furthermore, a change or rate of change overa series of samples may also be determined. The level of noise in aparameter value is another parameter that can be determined. Therefore,the parameters can be provided for all types of physically detectablecharacteristics of the touch as well as derivations of these detectablecharacteristics. In addition, these characteristics may be operated onwith filters to smooth or otherwise process the data. For example, thenoise in a parameter may be filtered out. Thus, in at least someembodiments, the noise itself would be filtered while the level of noisewould be used as a parameter. Filters may provide additional types ofprocessing. For example, a centroid of the area of the touch may bedetermined so as to provide a more precise location of the touch. Inaddition, data points that suggest a fluctuation too fast to berepresentative of a human touch and/or an intended touch can befiltered. Numerous other filters may be used as desired.

Next in step 830, the reliability of the touch is determined. In anembodiment this can be done by the touch-sensitive device 165 itself.For example, looking at FIG. 11, a computing environment 100 includes atouch-sensitive surface 208 in communication with a firmware 1105. In anembodiment, the firmware may be software embedded into thetouch-sensitive device. The firmware 1105 may determine the reliabilityvalue based on a set of parameters. Depending on the type of hardware,components such as A/D converters and other known circuits may be placedbetween the touch-sensitive surface 208 and the firmware 1105 so as totransform the physical touch into digital data in a known manner. Forexample, a circuit that detects changes in resistance, which is ananalog measurement, could provide these changes to an A/D converter soas to translate the changes into digital values in a known manner.

In an embodiment, the firmware 1105 may be omitted and the reliabilitydetermination may be done by a driver 1112. As is known, a driver canprovide a level of abstraction that allows higher level programs, suchas an operating system, to communicate or receive information from aparticular piece of hardware but, unlike the firmware, a driver istypically provided separate from the hardware. In an alternativeembodiment, both a driver and firmware may be used in series or inparallel to transmit information to the software module 1115. In anotheralternative embodiment, the firmware 1105 may generate the set ofparameters and the driver 1112 may determine the reliability value. Ascan be appreciated, the firmware 1105 and the driver 1112 are bothexamples of a device driver that provides an interface between theoperation system and the specific hardware used by the touch-sensitivedevice 165.

The reliability may include a number of factors such as the value of oneor more parameters along with the rate of change of one or moreparameters. In at least some embodiments, the reliability can be aprobability that the touch is intended. For example, the height (h) andwidth (w) of a touch can be used to calculate a probability (p) that atouch was intended:

p=f(a)+f(s)

where f(a)=α/(ε+σh*w); and

f(s)=α/(ε+β|(h ² −w ²)|)

In the above equation, α, β, σ, and ε may represent constants (or morecomplex functions) that can be used to weight the importance of variousfactors, and f(a) represents some function of area while f(s) representsa function of shape, both of which are based on the height (h) and thewidth (w). In general, however, as can be appreciated from the aboveequation, the probability that the touch is an intentional touchincreases as the area of the touch decreases and the probability alsoincreases the more closely the shape of the touch has the same heightand width. As can be readily appreciated from this example, a largenumber of variations in how the reliability is determined are possible.In an alternative embodiment, the reliability may be a sum of the numberof parameters that are within an accepted range. Thus, there are analmost unlimited number of variations in how the reliability value maybe determined, subject to inherent limitations or unique characteristicsof the hardware chosen.

After the reliability value is determined, in step 835 the touch data iscommunicated (e.g. transmitted) to the software module 1115 (FIG. 11)which uses the reliability value to generate a confidence level. Thesoftware module may be part of the operating system or some otherseparate software module that is configured to receive the reliabilitydata. The touch data may include just the reliability value and alocation of the touch or it may include additional details of theparameters, as desired.

In at least some embodiments, the firmware 1105 and/or the driver 1112can be configured to process a sufficient number of variables so as tomake the reliability value, which may also be an array of values, morevaluable. In an alternative embodiment, the firmware 1105 and/or thedriver 1112 may make minimal calculations and allow the software moduleto analyze more of the data. In such an embodiment, the parameters maybe observable features without derived values and the confidencedetermination may include calculations related to changes in theparameters over time.

As briefly noted above, typically a touch will change over time, eitherin location or shape or size or some other parameter. For example, FIG.9 illustrates a touch-sensitive device 165 with a touch-sensitivesurface 208. Depicted on the touch-sensitive surface 208 are fivetouches 901-905. The touches 901-905 represent 5 touches detected insubsequent intervals. As can be appreciated, touches 901-905 may be thesame touch over time or may actually be different touches. Whiledepicted as being similar, values for some or all of the parameterspreviously discussed may be different for some or all of touches901-905.

Turning to FIG. 10, a diagram for a data structure holding data relatingto multiple touches is provided. P1-1 represents a first parameter ofthe touch 901, P1-2 represents a first parameter of touch 902, P1-3represents a first parameter of touch 903, P1-4 represents a firstparameter of touch 904 and P1-5 represents a first parameter of touch905. Similarly, P2-1 through P2-5 represent a second parameter fortouches 901-905, respectively. In at least some embodiments, the firstparameter is an area of the touch and the second parameter representsthe shape of the touches. It should be noted that additional parametersmay be added and that the parameters P1 and P2 may represent any otherparameters desired. For example, a parameter for location or velocity oracceleration of the touch may also be included. It should be noted thata parameter based on a change over time such as velocity will initiallyhave a value of zero but, assuming a reasonably high sampling frequency,will quickly become some non-zero value.

Once the parameters for the touches are determined, a reliability valueR1 through R5 may be determined for each of the touches 901-905,respectively. As can be appreciated, the reliability of each of thetouches 901-905 depends on values of P1 and P2, thus each of thereliability values R1-R5 for each of the touches 901-905 may beindependent of the other reliability values.

Once the reliability value for the touch is determined, it can becommunicated or transmitted to the software module 1115 (FIG. 10). In anembodiment, the software module may be, without limitation, theoperating system 134 (FIG. 1). The software module 1115 then uses thereliability value to determine a confidence value. FIG. 12 illustratesan embodiment of such a determination.

First in step 1205, the reliability data is received. In at least someembodiments, the reliability data may include the reliability value anda location of the touch. In an alternative embodiment, the reliabilitydata may include the reliability value, the location of the touch andone or more additional parameters.

Next in step 1220, the software module determines a location context.This can be done by querying a software application 135. The locationcontext is part of an activity context, and the location contextincludes the location of various windows or regions on the display alongwith their intended use. Referring back to FIG. 5, a touch may belocated in the window 530, in the window 535, in the window 550 or notin any of the above windows. Different applications may vary thetreatment of touches in different windows. In an embodiment, anapplication may ignore any touch outside the window 530. In anotherembodiment, an application may accept certain types of gestures in thewindow 535. In yet another embodiment, any touch in the window 550 maytrigger an action. This latter embodiment may be useful if the window islocated in a position of the touch-sensitive surface that is unlikely tobe inadvertently touched. In yet another embodiment, an application mayrequire a more perfect touch, thus causing a greater range of touches tobe rejected within the window 530.

As can be appreciated, variations are possible and differentapplications can reject or accept different ranges of touches so as tooptimize the rejection of unintentional touches versus the accidentalrejection of intentional touches. And for certain windows where an inputis desired, any touch may be sufficient. Therefore, the location contextprovides information to the software module regarding what window orapplication is or would be affected by touch and what range of touches(e.g. the needed confidence level for a touch) are acceptable in thatwindow or area. It should be further noted that if desired, the range ofacceptable touches may be user configurable.

Next in step 1225, the software module determines the variability in thereliability value. Referring back to FIG. 9, in an embodiment where thetouches 901-905 represent the same touch over time, the touch may have ahigh reliability value for R1, R3 and R5 and a low reliability value forR2 and R4. The expected behavior for an intentional touch is a moreconsistent reliability value; therefore such a variation in reliabilitywould suggest the touch should be rejected. For example, a palm restingon a touch-sensitive surface while the user was using a stylus wouldtypically progress through a range of shapes and sizes in the touch asthe user moved his or her hand across the touch-sensitive surface.

Next in step 1230, the state of an active application, which may also bepart of the activity context, is considered. This may include the timethe application has waited for an input, the type of input expected andhistorical patterns of input, to mention a few variations. For example,if a user has consistently used a stylus to enter data in an applicationwindow, then a touch in that window that does not match the stylus maybe initially rejected. As a user may interact in a unique manner withdifferent applications, this allows each application to be treateduniquely.

Next in step 1235 a confidence level is determined. The confidence levelincorporates one or more factors of the reliability of the touch alongwith the activity context to make a more informed decision of whether toreject the touch. Thus, the confidence level combines one or morefactors related to reliability with one or more factors related toactivity context. It should be noted that the reliability factors mayinclude a determination of an average reliability over a greater periodof time, which may be one to five seconds and may also includevariations in the reliability over time. As can be appreciated, theactivity context can vary and may include, but is not limited to, adetermination of whether the location of the touch is in a windowassociated with an application, a determination of an activeapplication, a determination that the area being touched is an activearea, a determination of whether multiple touches are being madesubstantially simultaneously, a determination of whether multipletouches are expected, a determination of whether a profile of the touchmatches a known gesture, a determination of how a particular applicationtreats touches, and a determination of whether another valid touch isbeing made in a different location on the touch-sensitive display.Therefore, the calculation of the confidence level may be any desirablealgorithm and may vary with particulars of hardware implementations.

It should be noted that the confidence level may also involve aconsideration of parameters used to determine the reliability value.Historical variations in a particular parameter such as the velocity,direction of movement or the number of points of contact of a touch(which are really the composite of a number of touches that can belinked together because of their proximity and the frequency ofsampling) may also be considered. For example, while the firmware maydetermine that the touch has a low reliability, the software module maydetermine that the touch represents a gesture specific to an applicationand therefore an appropriate input may be transmitted to theapplication. This allows customized gestures to be associated with eachapplication, even if the gestures are not recognized by the firmware orthe driver. However, the firmware or driver may also include the abilityto recognize certain gestures. Therefore, as can be appreciated,numerous variations exist in how the parameters related to the touch arehandled.

Next in step 1240, a comparison of the confidence level to apredetermined level is made. As noted above, the predetermined level maychange depending on a number of factors such as, but not limited to, thelocation of the touch and which application is active. If the confidencelevel of the touch meets the predetermined level, then in step 1245 thetouch is communicated or transmitted to the application as an input. Ifthe confidence level of the touch does not meet the predetermined level,then in step 1250 the touch is rejected.

It should be noted that additional steps may be added to the abovemethod and that steps may be combined or omitted as desired.

Turning to FIG. 13, an embodiment of a two step method of evaluating aconfidence level of a touch is disclosed. As can be appreciated, themethod of FIGS. 12 and 13 could be combined. First in step 1310, a checkis made to see if the confidence level of the touch exceeds apredetermined level. If the confidence level does exceed thepredetermined level, then in step 1315 an input associated with thetouch is communicated or transmitted to the application.

If the confidence level of the touch does not meet the predeterminedlevel, then in step 1320 a second check is made to see if the confidencelevel of the touch exceeds a threshold level. If the confidence leveldoes exceed the threshold level, in step 1325 a visual feedback isprovided to the user. In at least some embodiments a cursor or a widgetor some other graphical indicator may be moved to or near the locationwhere the touch is located. However, if the input fails to meet thethreshold level, in step 1330 the touch is rejected.

It should be noted that as the touch probably represents a finger orpalm, it may be useful to make the cursor, or whatever graphicalfeedback is used, observable even if the user's hand is partialoccluding a portion of the display. In an embodiment, a widget, such asa graphical user interface that may be used to provide additionalprecision when a user is interacting using a finger, may be positionednear the touch contact. As can be appreciated, this provides the userwith feedback that something has caused the widget to move. The user canappreciate that an inadvertent touch may have caused the widget to move.However, no actual input will be transmitted in this embodiment;therefore the user does not have to undo something that wasunintentional. Furthermore, if the user intended to provide an input butdid so in a manner that is interpreted as a low confidence level touch,the user will be able to use the widget to provide the desired input andwill not be frustrated by the rejection of intentional input.

Returning to FIG. 10, as can now be appreciated, the confidence levelsC1-C5 may be related. In an embodiment, each of the columns represents asubsequent period of time for the same touch. An initially high R1 valuemay not provide a high confidence level because of the limitedhistorical knowledge regarding the touch. As the reliability valuecontinues to be high for R2-R5, however, the historical values and aminimal amount of variability allow the confidence level to be generatedas high for all the touches represented by each column. Thus, thedetected touches may be treated as intentional touches.

Conversely, if the reliability value fluctuates with time or the touchmoves outside an expected region of contact, the confidence level, whichmay have started out higher, will drop. Therefore, it may be useful todelay the decision of whether to communicate the touch as an input or toreject it.

While delaying the determination of whether to reject the touch allowsfor a more accurate determination, the user typically wants the system'sresponse to be fluid and immediate. To minimize the user's perception ofthe delay, therefore, the reliability data can be transmitted asgenerated and the software module 1115 (FIG. 11) can control the delay.The delay may be varied depending on the confidence level, the locationof the touch and the state of an application (e.g. whether theapplication is expecting an input). While not required, the reliabilityvalue and other data associated with the touch may be transmitted to thesoftware module 1115 using a universal serial bus 2.0 protocol. As canbe appreciated, the advantage of using such a protocol is theavailability of relatively high bandwidths, thus even relatively highsampling frequencies may be used effectively. In addition, an increasedbandwidth allows greater levels of detail to be passed along so that theconfidence level determination may take into account additionalinformation.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims. Numerous other embodiments,modifications and variations within the scope and spirit of the appendedclaims will occur to persons of ordinary skill in the art from a reviewof this disclosure.

1. A method comprising: receiving, by a computer, a first touch on atouch-sensitive device of the computer, the first touch having a firstwidth and a first length; determining, by the computer, a firstreliability value of the first touch based at least partly on the firstwidth and the first length, the first reliability value indicating afirst probability that the first touch is intentional; receiving, by thecomputer, a second touch on the touch-sensitive device after receivingthe first touch, the second touch having a second width and a secondlength; determining, by the computer, a second reliability value of thesecond touch based at least partly on the second width and the secondlength, the second reliability value indicating a second probabilitythat the second touch is intentional; determining, by the computer, thatthe first touch and the second touch are each a portion of a third touchbased at least partly on changes to the first reliability value and thesecond reliability value over time, the third touch having a third widthgreater than a combination of the first width and the second width and athird length greater than a combination of the first length and thesecond length; and rejecting, by the computer, the third touch based atleast partly on the third width and the third length.
 2. The method asrecited in claim 1, further comprising determining a confidence value ofthe first touch based at least partly on the first reliability value. 3.The method as recited in claim 2, further comprising: determining thatthe confidence level of the first touch does not exceed a predeterminedlevel; and determining that the confidence level of the first touch doesexceed a threshold level.
 4. The method as recited in claim 3, furthercomprising providing visual feed back to a user of the computer at leastpartly in response to determining that the confidence level of the firsttouch does not exceed the predetermined level and that the confidencelevel of the first touch does exceed the threshold level.
 5. The methodas recited in claim 4, wherein the visual feedback includes moving agraphical user interface indicator to a location where the first touchis located.
 6. The method as recited in claim 5, wherein the graphicaluser interface indicator is a cursor or a widget.
 7. One or morecomputer-readable storage media including computer-executableinstructions that, when executed by a processor, perform operationscomprising: detecting a touch by a touch-sensitive device of a computer;receiving, by the computer, reliability data associated with the touch,the reliability data indicating a location of the touch on thetouch-sensitive device; determining, by the computer, a location contextof the touch, the location context indicating a location of one or morewindows on the touch-sensitive device and a use of each of the one ormore windows; determining a state of a software application of thecomputer; determining a confidence level of the touch based at leastpartly on the location touch, the location context of the touch, and thestate of the software application; and communicating the touch to thesoftware application when the confidence level of the touch meets apredetermined level.
 8. The one or more computer-readable storage mediaas recited in claim 7, wherein the state of the application includes anamount of time the software application has waited for an input, a typeof input expected by the software application, historical patterns ofinput for the software application, or combinations thereof.
 9. The oneor more computer-readable storage media as recited in claim 8, whereinthe historical patterns of input for the software application aredifferent than historical patterns of input for an additionalapplication.
 10. The one or more computer-readable storage media asrecited in claim 7, wherein the determining the confidence level of thetouch includes determining whether the location of the touch is in awindow associated with the software application, determining whether thelocation of the touch is an active area of the touch-sensitive device,determining whether a valid touch is being made in a different locationon the touch-sensitive device, or combinations thereof.
 11. The one ormore computer-readable storage media as recited in claim 7, wherein theoperations further comprise determining an active application of thecomputer and the predetermined level depends at least partly on thelocation of the touch, the active application of the computer, or both.12. The one or more computer-readable storage media as recited in claim7, wherein the location context further indicates a window displayed onthe touch-sensitive device that is affected by the touch, a confidencelevel that is acceptable with respect to the window, or both.
 13. Theone or more computer-readable storage media as recited in claim 12,wherein the confidence level that is acceptable with respect to thewindow is user configurable.
 14. The one or more computer-readablestorage media as recited in claim 7, wherein the location contextfurther indicates that the software application ignores touches outsidea particular window of the touch-sensitive device, that the softwareapplication accepts certain types of gestures in the particular window,that any touch in the particular window triggers an action with respectto the software application, or combinations thereof.
 15. A systemcomprising: a touch-sensitive device; a processing unit; memory coupledto the processing unit, the memory storing: firmware configured todetermine a number of reliability values of a touch on thetouch-sensitive device; a software module configured to: determine afirst confidence level of the touch based at least partly on a firstreliability value of the touch; determine a second confidence level ofthe touch based at least partly on a second reliability value of thetouch, the second confidence level having a lower value than the firstconfidence level; and delaying a determination regarding whether toreject the touch based on a decrease in the confidence level of thetouch from the first confidence level to the second confidence level.16. The system as recited in claim 15, wherein the first reliabilityvalue and the second reliability value indicate a respective probabilitythat the touch is intended.
 17. The system as recited in claim 16,wherein the respective probability that the touch is intended depends atleast partly on an area of the touch, a correspondence between a heightof the touch and a width of the touch, or both.
 18. The system asrecited in claim 15, wherein an amount of delay associated with thedetermination regarding whether to reject the touch depends at leastpartly on a particular confidence level of the touch, a location of thetouch, a state of an application associated with the touch, orcombinations thereof.
 19. The one or more computer-readable storagemedia of claim 18, wherein the state of the application associated withthe touch includes an expectation that the application is expecting atouch.
 20. The one or more computer-readable storage media of claim 15,wherein the determination regarding whether to reject the touch isdelayed when reliability values of the touch fluctuate over time or thetouch moves outside an expected region of contact on the touch-sensitivedevice.